1. Field of the Invention
The present invention relates to setting a mode of an apparatus having a microprocessor control unit and, more particularly, to a reset device which selectively sets an operation mode of the component blocks of a system using a reset function, and a method of setting the driving mode using the reset device.
2. Discussion of Related Art
Generally, every apparatus including an MCU (microprocessor control unit) usually has a reset function. With the reset function, a part of the apparatus or the overall system is set to the initial state of the system established when the electric power is first supplied to the system. The reset function is necessary to restart the system when the system malfunctions due to noise and overheating.
FIG. 1 shows a block diagram of the structure of a conventional reset device. FIG. 2 shows a flow chart for illustrating a conventional reset operation of the conventional reset device.
As shown in FIG. 1, a reset signal input unit 1 inputs a reset signal to all component blocks for systematically initializing the driving mode of all the component blocks. The reset signal is most effective in simultaneously initialing all the component blocks. The component blocks include a register 2, a driving mode setting unit 3 and a port data register 4, and are driven normally or abnormally.
As shown in FIG. 2, if the reset signal from the reset signal input unit 1 is input to the system while any one of the component blocks is operating normally or abnormally (step S1), all the component blocks stop their operations (step S3). Then the driving mode of the overall system is initialized (step S4). If the reset signal is not input, each component block continues its present operation (step S2). In the initializing step (S4), a resetting function is performed as follows.
If the apparatus having the MCU operates in an abnormal manner, the reset signal is input to discontinue the abnormal operation of the apparatus and to initialize the apparatus immediately. The reset signal is generated according to the user's selection. If the apparatus is operating normally, the present operation is completed and then the apparatus returns to its initial state to perform other operations.
However, the above conventional reset operation automatically initializes the entire system without considering whether the operation of each component block prior to the reset signal is normal or abnormal. The reset signal initializes even the component blocks of the system which do not require resetting. Therefore, many component blocks of the system are unnecessarily reset to the initial state, which wastes power and operation time and results in a decreased efficiency.